The present invention relates to a cross clamping device to clamp two bars, which are rotated by 90° to each other.
In the context of this patent application, sheet metal strips and the like are also subsumed under the term bar.
There are many possibilities to connect two bars which are perpendicular to each other. For example, both bars can be directly screwed onto a common connection piece independently of each other, which has the disadvantage however that the bars must be provided with screw holes. In order to avoid this, both bars can be clamped independently from each other, each between two clamping pieces, which are connected with the clamping pieces of the other bar. The clamping pieces clamping a bar can be screwed together, such that the clamping force is produced by the action of screwing the pieces together. A disadvantage of this method of connection is that rather a lot of, or otherwise complicated, individual parts are necessary, in particular two screws per bar, if a good clamping effect is required.
In view of the disadvantages of the aforementioned types of connection, the object of the invention is to provide a device to connect two bars which are perpendicular to each other, which has a few simple individual pieces, with which a stable connection can be produced.
This object is achieved by the cross clamping device of this invention, which is characterized by the features of the following description and the appended claims.
The essence of the invention is the following: a cross clamping device comprising a base plate, which has a first and a second leg and a clamping piece which connects the two legs together, a first clamp, which is screwed onto the first leg by means of a first screw, and a second clamp, which is screwed onto the second leg by means of a second screw. The base plate and the two clamps are designed such that a first bar is able to be clamped between the first and the second clamp and a second bar is able to be clamped between the two clamps and the clamping piece of the base plate, the second bar being rotated by 90° in relation to the first bar. The first and the second screw each have a head, which is at least partially conical shaped, so that by the tightening of the first and of the second screw, the first and the second clamp are pressed against the first bar by the slanting conical surface and the two bars are clamped.
By the tightening of the first and of the second screw, the particular screw head, owing to the slanting surface, pushes the relevant clamp against the first bar. In this manner a clamping force can be produced perpendicular to the direction of screwing, which brings about the clamping of the first bar between the two clamps.
A significant advantage of the cross clamping device of this invention is that by means of tightening the two screws, the first bar, which is arranged between the first and the second clamp, as well as the second bar, which is arranged between the two clamps and the clamping piece of the base plate, are clamped, i.e. the two screws perform a double function, so that separate screws for the clamping of the first bar and the clamping of the second bar are not necessary. That helps to keep the number of parts low. Also by using few individual parts and by their optimal combination, it makes the device easy to clean. Since the screws perform a double function, this additionally has the advantage that the first and the second bar can be more quickly connected with each other by means of the cross clamping device of this invention.
The cross clamping device of this invention can, in particular, be employed everywhere where rails, guides, supports and the like lie on traverse bearing rods and must be held in place.
With an embodiment of the cross clamping device of this invention, which is preferably used for certain purposes, at least one of the two clamps is additionally screwed on the accompanying leg of the base plate by means of a further screw. In this manner a stronger clamping of the first bar between the two clamps can be achieved, which can be useful for heavy loads.
Preferably each of the screws has a shaft with a thread and also has a head, while the first leg of the base plate has at least a first hole with a thread, into which the first screw is screwed, and the second leg of the base plate has at least a second hole with a thread, into which the second screw is screwed. The screws are screwed with the shaft into the threaded holes in the legs of the base plate, while the heads of the screws press the clamps against the base plate.
Preferably at least one of the two clamps has a through hole, whose diameter, at least in a direction towards the first bar, is greater than the diameter of the screw shaft. Thereby the screw in the through hole is a little loose, so that the clamps can be at least a little displaced perpendicular to the screw and so a clamping force can be produced on the first bar.
Preferably the through hole, or more specifically at least one of the through holes, has an enlargement which is on the side opposite from the base plate, in which the head of the accompanying screw is at least partially inserted. This at least partial sinking of the screw head in the enlargement ensures that the screw does not project out, or at least does not project so far out of the clamp. The cross clamping device is thereby made easier to clean.
Preferably the enlargement, at least on the side which is on the same side as the first bar, is bordered by a slanting surface of the clamp, such that by the tightening of the screw, the clamp is pressed against the first bar by the screw which is pressing on the slanting surface. In this manner a clamping force can be produced which is perpendicular to the direction of screwing, which achieves the clamping of the first bar between the two clamps. Optimally, at the same time, the head of the screw is at least partially conical shaped, as previously described, such that two slanting surfaces come to lie on each other.
Preferably the clamping piece of the base plate is thinner than the two legs and/or the clamps are thinner in the region of the clamping piece of the base plate than in the region of the legs, so that a space exists between the two clamps and the clamping piece of the base plate, in which the second bar is able to be clamped, while the clamps lie on the legs. Such a form of the base plate and of the clamps guarantees a strong clamping of the second bar in a compact cross clamping device without spaces which are susceptible to dirt.
In a preferred embodiment the two clamps each have at one their ends a projection which extends to the other clamp, in which the two projections touch each other. By the tightening of the screws the touching projections achieve a slight turning of the clamps, which strengthens the clamping of the first bar.
Preferably the two clamps lie flat on the first bar and on the second bar. Thereby a flat and more stable transmission of the clamping force is guaranteed.